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Theme 2: Biodiversity & Ecosystems
Topic: Bio-indicators
What is a bio-indicator?
The term 'bio-indicator' comes from two words 'biological' and 'indicator'. A bio-indicator is a living organism that is able to tell us whether our environment is healthy or unhealthy.
Why are frogs good bio-indicators?
Frogs are well known for their sensitivity to pollution and habitat degradation. They need a healthy environment, both on land and in water, to complete their life cycle from egg to tadpole to adult. Polluted water that may contain chemicals such as fertilizers or detergents can significantly impact on frog populations. Therefore, unhealthy habitats have reduced frog populations.
Frog eggs and tadpoles are most sensitive to pollution or environmental change because they are permanently in the water. The eggs are covered in a soft jelly-like substance that does not protect the embryo from pollutants in the water. Pollutants commonly result in the death of the egg or tadpole, but may result in the production of abnormalities of soft and/or skeletal tissues that can later be seen in the adult frog. Abnormalities are seen in every species of animal. It is only when you find an unusually high number of frogs with crooked spines and extra legs or arms that you know there is something wrong in the environment.
Macroinvertebrates as bio-indicators
Aquatic macroinvertebrates are also often used as a bio-indicator.
What is an aquatic macroinvertebrate?
Aquatic macroinvertebrates is the technical term for a water bug. 'Aquatic' means freshwater, 'macro' means you can see it with your eyes and an invertebrate is an animal without a backbone.
Where are they found?
Aquatic macroinvertebrates are found in most creeks, rivers, lakes and wetlands. However, you will not find them in estuarine areas, as they generally live in freshwater. At your local waterway you can find them under rocks, in the mud on the bottom, amongst the reeds, on the water surface and swimming in open water.
Aquatic macroinvertebrates are pollution indicators!
You can use aquatic macroinvertebrates to get an estimate of the amount of pollution in a waterway. A very polluted stream will only have a few types of macroinvertebrate living there. A less polluted stream will usually have more invertebrate species. Find out all about South Australia's aquatic invertebrates from the Waterwatch 'Critter Catalogue': www.sa.waterwatch.org.au/education.htm#new
Sensitive or tolerant to pollution?
Some invertebrates are sensitive to pollution while others are pollution tolerant. In fact, scientists have grouped the macroinvertebrates found in our region into four pollution groups. These groups are classified as very sensitive, sensitive, tolerant and very tolerant.
Imagine a healthy stream with many water-bugs living in it. If a small amount of pollution were present, then the water-bugs in the very sensitive bugs category would disappear. If the water were to become more polluted, then sensitive water-bugs would die and so on. So, if on inspecting a local waterway, you find no invertebrates at your site, this may be a sign of a very polluted waterway. If you find a mix of sensitive and tolerant water-bugs then you can be assured that the pollution level in the waterway is low.
Why else might cause the aquatic macroinvertebrates to disappear?
Heavy rainfall can cause many creek animals to be flushed downstream. So if you sample a water in a local creek or river after heavy rain, you may find fewer water-bugs present. During cooler months, the breeding activity of some bugs is lower, and therefore, less kinds of water-bugs may be found.
Student Activity Ideas
- Visit your local waterway to look at the habitat. Look at human impacts and water quality at the site. Listen (and perhaps record) any frogs that you hear.
- Visit your local waterway and listen and record the frog calls over the term/year. Are frogs present or absent from the site? Students to look at the habitat and surrounding area to determine what factors may be affecting frog numbers.
- Participate in the EPA Frog Census program held annually in September. (www.epa.sa.gov.au/frogcensus)
- Discuss with students some pollutants that may affect the egg and tadpole health.
- Create a habitat. Students to draw a creek or wetland on a large sheet (at least A3) and divide the drawing into half. Half becomes an example of a good frog habitat and the other side a poor habitat.
Students could use magazine cutouts, rubbish found in the school yard, fallen leaves or their own drawings to help create the scene.- Play 'celebrity frog'. Write down on cardboard, six frogs found in your catchment. Select six students to be the celebrity frogs. Provide each student with their identity. Each student must then ask the remainder of the class a series of questions so that each frog can be identified.
- Research the cane toad. What could happen if they were introduced to SA? Look at all of the current factors that are affecting frogs in your catchment.
Enquiry Learning
- How can animal species be used to indicate the health of different environments?
- What types of monitoring can be effectively used by students to assess the health of environments?
- Which species such as macroinvertebrates and frogs can be monitored to assess the quality of water and the health of riparian zones?
- Which species can be monitored to assess the overall health of catchment environments? (Look at birds, reptiles, fish, butterflies, macroinvertebrates and frogs. There are many more too! )
Internet Resources
Type Description Resources Covering the Topic Easy
- Introduction to frogs.
Onkaparinga Catchment Water Management
/www.onkaparinga.net/education/
downloads/folder_2/
15i_frogs.pdf
- Introduction to aquatic invertebrates.
Onkaparinga Catchment Water Management Board
www.onkaparinga.net/education/
downloads/folder_2/
13i_macros.pdf
- Birds as bioindicators.
Onkaparinga Catchment Water Management
www.onkaparinga.net/education/
downloads/folder_2/
19i_birdasbio.pdf
- The state of health of the Mt Lofty catchment.
- Aquatic ecosystems in the Mt Lofty Ranges. Looks at macroinvertebrates, vertebrates, fish and frogs.
- Clear summary of the issues.
The Mt Lofty Ranges Watershed Protection Office - EPA
www.dehaa.sa.gov.au/epa/pdfs/
fact3.pdf
- Why monitor frogs?
- Brief explanation of bioindicator species.
SA EPA
www.environment.sa.gov.au/epa/
frogcensus/about.html
- Biological monitoring.
- What can be monitored through Waterwatch.
SA Waterwatch
www.sa.waterwatch.org.au/
monitor.htm#techniques
- The Frog Files.
- Information about frogs.
Western Wildlife
www.westernwildlife.com.au/frogs/
index.htmMore Comprehensive
- Biological indicators - a summary.
NSW EPA
www.epa.nsw.gov.au/soe/soe2000/
cw/cw_5.2.htm#cw_5.2_h005
- The national community based water quality monitoring program.
- Good summary of waterway monitoring.
Waterwatch Australia
www.waterwatch.org.au/library/
involve.html
- Macroinvertebrates and water quality in WA.
- PDF download covering the main issues.
Water Resources WA
www.wrc.wa.gov.au/public/
waterfacts/2_macro/WF2.pdfMore Complex
- Ecowatch: Restoration ecology and the use of bioindicators.
- PDF download with excellent introduction to the main issues of regeneration and use of macroinvertebrates as bioindicators.
CSIRO
www.ento.csiro.au/Ecowatch/
Images/ecowatch.pdfActivities
Band Activity Contact Early Years
- Scrape, Jiggle and Wiggle.
- Takes you through how to monitor for macroinvertebrates.
Onkaparinga Catchment Water Management Board
www.onkaparinga.net/education/
downloads/folder_2/
14i_scrape.pdf
- Which frog am I
- Exercise to identify local South Australian frogs.
Onkaparinga Catchment Water Management Board
www.onkaparinga.net/downloads/
own/frog.doc
- How to make a simple stocking net.
Onkaparinga Catchment Water Management Board
www.onkaparinga.net/downloads/
own/nets.doc
- Participate in the annual frog census.
SA EPA
www.environment.sa.gov.au/epa/
frogcensusPrimary Years
- What is a macroinvertebrate?
- Discover why macroinvertebrates are bioindicators of water health.
Onkaparinga Catchment Water Management Board
www.onkaparinga.net/caring/
waterwatch.shtml#aquatic
- Macro Id Chart
- Learn more about the bugs in our waterways.
Onkaparinga Catchment Water Management Board
www.onkaparinga.net/downloads/
own/macro_id.pdf
- Frog Lifecycle.
- Visually demonstrates the lifecycle of a frog.
Onkaparinga Catchment Water Management Board
www.onkaparinga.net/education/
downloads/folder_2/
15a_frogcycle.pdf
- 'A Frog's Life'.
- Learn about biological monitoring and why frogs are used as indicators of water health.
KESAB Patawalonga and Torrens Waterwatch
www.cwmb.sa.gov.au/kwc/
section3/frog_pack_2003.pdf
- Participate in the annual frog census.
SA EPA
www.environment.sa.gov.au/epa/
frogcensusMiddle Years
- How to build a frog pond.
Environment Australia
www.ea.gov.au/education/facts/
frogpond.html
- Participate in the annual frog census.
SA EPA
www.environment.sa.gov.au/epa/
frogcensusWho Can Help?
Organisation Who Can Help? All catchments EPA Community Monitoring Section (including Waterwatch and Frog Census)
Adelaide Metropolitan Area Urban Forest Biodiversity Program Metropolitan Catchment Water Management Boards Catchment Care - North Adelaide and Barossa Catchment Water Management Board (CWMB)
Waterwatch SA Waterwatch: Broughton Wakefield
Waterwatch: KESAB Patawalonga & Torrens
Waterwatch: North Adelaide & Barossa
Waterwatch: River Murray (Upper)
